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Getting Organized with Service Discovery for Microservices

Getting Organized with Service Discovery for Microservices

Microservices are small and enable you to go fast. But you’ll need to get them organized: this is where Service Discovery comes into play. There are several open source solutions available: HashiCorp Consul, CoreOS etcd and Netflix Eureka. But how should we handle security, multiple datacenter and monitoring? And how to look up the services from your services? This session will gives an overview of the tools available and their utilities with practical examples.

Alexander Schwartz

May 04, 2016
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  1. .consulting .solutions .partnership
    Getting Organized with
    Service Discovery for Microservices
    Alexander Schwartz, Principal IT Consultant
    Continuous Lifecycle London 2016 – 4 May 2016

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  2. Getting Organized with Service Discovery for Microservices
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 2
    Everyday life in the cloud
    1
    etcd: Central Configuration Store
    2
    Consul: Service Discovery, Configuration and Monitoring
    3
    Eureka: Availability First!
    4
    Service Discovery Comparison
    5

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  3. My sponsor and employer – msg systems ag
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 3
    Founded in 1980
    More than 5.500 employees
    727 M € (573 M £)
    turnover in 2015
    Offices in 24 countries
    Headquarter based
    near Munich in Germany

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  4. That‘s me – Alexander Schwartz
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 4
    14 years of Java
    7 years of PL/SQL
    7 years of
    consumer finance
    3.5 years direct banking
    1 wife
    2 children
    471 found
    Geocaches
    @ahus1de

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  5. Getting Organized with Service Discovery for Microservices
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 5
    Everyday life in the cloud
    1
    etcd: Central Configuration Store
    2
    Consul: Service Discovery, Configuration and Monitoring
    3
    Eureka: Availability First!
    4
    Service Discovery Comparison
    5

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  6. Everyday life in the cloud
    A simple Cloud Setup
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 6
    Where are my application servers?
    Where is my database?

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  7. Everyday life in the cloud
    A simple Cloud Setup
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 7

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  8. Everyday life in the cloud
    A simple Cloud Setup
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 8

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  9. Everyday life in the cloud
    Configuration at runtime saves you the hassle – and maintenance windows
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 9
    • Change parameters at runtime
     Target-IPs of servers
     Names of input and output folders
     Timeouts and other business parameters
    • Central database for
     Configuration parameters
     Service-Discovery for Clients
     Service-Discovery for Load Balancers

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  10. Getting Organized with Service Discovery for Microservices
    10
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016
    Everyday life in the cloud
    1
    etcd: Central Configuration Store
    2
    Consul: Service Discovery, Configuration and Monitoring
    3
    Eureka: Availability First!
    4
    Service Discovery Comparison
    5

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  11. CoreOS etcd
    etcd is a Central Configuration Store
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 11
    Suitable for configuration and service discovery
    • Simple: HTTP/REST w/ JSON
    • Reliable: highly available and consistent
    • Secure: optionally with SSL-Client-Certificates
    • Fast: several thousand write operations per second
    Operations: GET/PUT/DELETE/CAS/WAIT/TTL
    # PUT
    curl -L -X PUT http://127.0.0.1:4001/v2/keys/foo-service/container1 –d value="localhost:1111"
    # GET
    curl -L http://127.0.0.1:4001/v2/keys/foo-service/container1
    # WAIT
    curl -L http://127.0.0.1:4001/v2/keys/foo-service?wait=true\&recursive=true...

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  12. CoreOS etcd + Hightower´s confd
    When values change, confd will update your Configuration Files
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 12
    confd

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  13. CoreOS etcd + Hightower´s confd
    When values change, confd will update your Configuration Files
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 13
    • Service templates (*.toml)
    • Configuration templates (*.tmpl)
    # nginx.toml
    [template]
    src = "nginx.tmpl"
    dest = "/etc/nginx/sites-enabled/app.conf"
    keys = [ "/foo-service" ]
    check_cmd = "/usr/sbin/nginx -t"
    reload_cmd = "/usr/sbin/service nginx reload"
    # nginx.tmpl
    upstream app_pool {
    {{ range getvs "/foo-service/*" }}
    server {{ . }};
    {{ end }}
    }
    confd

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  14. CoreOS etcd + Jurmous’ Java Client
    Use Jurmos’ Java Client to talk to etcd
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 14
    • Java-API for all of etcd’s API calls
    • Implemented on top of Netty (for asynchronous, non-blocking IO)
    // Simple put
    etcd.put("/foo-service/container1","localhost:1111").send();
    // Wait for next change on foo
    EtcdResponsePromise promise = etcd.getDir("/foo-service/")
    .recursive().waitForChange().send();
    // Java 8 lambda construction
    promise.addListener(promise -> {
    // do something on change
    });

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  15. CoreOS etcd
    Pros and Cons etcd
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 15
    Pro:
    • Easy access (REST), simple installation (Go-Binary), transport security (SSL)
    • Changes are published to the clients immediately
    • Generic structure for flexible usage
    • Used by CoreOS and Kubernetes
    Contra:
    • No access controls for on a per client level
    Add-ons:
    • Vulcan (HTTP Load Balancer, configuration stored directly in etcd)
    • SkyDNS (Service discovery via DNS, data stored in etcd)

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  16. Getting Organized with Service Discovery for Microservices
    16
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016
    Everyday life in the cloud
    1
    etcd: Central Configuration Store
    2
    Consul: Service Discovery, Configuration and Monitoring
    3
    Eureka: Availability First!
    4
    Service Discovery Comparison
    5

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  17. Hashicorp Consul
    Consul
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 17
    Built for Service Discovery, Configuration and Monitoring
    • Easy to use: HTTP/REST w/ JSON
    • Reliable: highly available and consistent
    • Secure: built in Access Control Lists and Encryption
    Main Sponsor: HashiCorp (the ones also building Vagrant)
    Homepage: https://www.consul.io/

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  18. Netflix Ribbon
    Ribbon
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 18
    Built for client side load balancing
    • Ribbon is well integrated into Feign: type safe web APIs
    Main-Sponsor: Netflix
    Homepage: https://github.com/Netflix/ribbon/

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  19. Consul and Ribbon
    The Client contacts available Services directly
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 19
    Consul-Server
    (for Key Value Store
    und Service Catalogue)
    Services
    Client

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  20. Services with Consul
    Every Consul Instance knows about its local Services
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 20
    "service": {
    "name": "web",
    "tags": ["master"],
    "port": 80
    }

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  21. Services with Consul
    Every Consul Instance checks its local Services
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 21
    "check": {
    "id": "http",
    "name": "HTTP API on port 80",
    "http": "http://localhost:80",
    "service_id": "web",
    "interval": "10s",
    "timeout": "1s"
    }
    "check": {
    "id": "script",
    "name": "Script Check",
    "script": "/usr/local/bin/check_mem.py",
    "service_id": "web",
    "interval": "10s"
    }
    "check": {
    "id": "ttl",
    "name": "Web Status",
    "service_id": "web",
    "ttl": "30s"
    }

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  22. Services with Consul
    Consul UI
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 22

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  23. Services with Consul
    Lookup Services using DNS SRV Records
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 23
    $ dig @127.0.0.1 -p 8600 web.service.dc1.consul. SRV
    web.service.dc1.consul. 0 IN SRV 1 1 80 web2.node.dc1.consul.
    web.service.dc1.consul. 0 IN SRV 1 1 80 web1.node.dc1.consul.
    web1.node.dc1.consul. 0 IN A 192.168.23.21
    web2.node.dc1.consul. 0 IN A 192.168.23.22

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  24. Consul and Ribbon
    Application Code for Ribbon
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 24
    MyService api = Feign.builder()
    .contract(new JAXRSContract())
    .encoder(new JacksonEncoder())
    .decoder(new JacksonDecoder())
    .client(RibbonClient.builder()
    .lbClientFactory(new ConsulLbFactory())
    .build())
    .target(MyService.class, "http://web");
    api.call();

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  25. public class ConsulLbFactory implements LBClientFactory {
    private Map clients = new HashMap<>();
    public synchronized LBClient create(String clientName) {
    LBClient client = clients.get(clientName);
    if(client == null) {
    ILoadBalancer lb = new ConsulLoadBalancer(clientName);
    IClientConfig clientConfig = new DefaultClientConfigImpl();
    clientConfig.loadDefaultValues();
    client = LBClient.create(lb, clientConfig);
    clients.put(clientName, client);
    }
    return client;
    }
    }
    Consul and Ribbon
    Java-API for Consul
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 25
    public class ConsulLoadBalancer extends BaseLoadBalancer {
    public ConsulLoadBalancer(String serviceName) {
    Consul consul = Consul.builder().build();
    HealthClient client = consul.healthClient();
    ServiceHealthCache svHealth = ServiceHealthCache.newCache(client, serviceName);
    svHealth.addListener(map -> {
    List newServers = new ArrayList<>();
    map.forEach((hostAndPort, serviceHealth) ->
    newServers.add(new Server(hostAndPort.getHostText(),
    hostAndPort.getPort())));
    setServersList(newServers);
    });
    /* ... */
    }
    }

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  26. Consul and Ribbon
    Pros and Cons Service Discovery with Consul
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 26
    Pro:
    • Contact to Services without a Single Point of Failure
    • Ready to use Libraries available
    • Decentralized monitoring of services
    • GUI for key value store and monitoring
    • Semantic of services instead of key value store only
    Add-ons:
    • eBay Fabio (HTTP Load Balancer, configuration directly in consul)
    • consul-template (writes configuration files like confd)
    • Nomad (scheduler that registers service automatically with consul)

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  27. Getting Organized with Service Discovery for Microservices
    27
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016
    Everyday life in the cloud
    1
    etcd: Central Configuration Store
    2
    Consul: Service Discovery, Configuration and Monitoring
    3
    Eureka: Availability First!
    4
    Service Discovery Comparison
    5

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  28. Netflix Eureka
    Eureka
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 28
    Build for Service Discovery inside Amazon Web Services (AWS)
    • REST: you choose from JSON and XML
    • Simple: Client-Pull
    • Reliable: highly available, availability before consistency
    Main Sponsor: Netflix
    Homepage: https://github.com/Netflix/eureka

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  29. Netflix Eureka
    Brewers CAP Theorem
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 29
    „A distributed system can fulfil only two out of three availability modes at a time.“
    Consistency
    Here: After a service registered, clients can find it (Linearizability).
    Availability
    Here: Service registration and lookup available for clients.
    Partition Tolerance
    Hier: Service registration and lookup work even in the presence of networks being partly unavailable.

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  30. Netflix Eureka
    Eureka – Availability first (1/2)
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 30
    Etcd:
    • Registration: CP
    • Lookup: AP (Standard) or CP („?quorum=true“)
    Consul:
    • Registration :
    CP for Key-Value-Store
    AP for Service-Registration and Health via local Agents („Anti-Entropy“)
    CP for combining the Information in the Service-Registry
    • Lookup via REST API: either CP („?consistent“),
    with the currently known leader, or AP („?stale“)
    • Lookup via DNS: with the currently known leader,
    alternatively AP with an upper time limit „stale reads“

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  31. Netflix Eureka
    Eureka – Availability first (2/2)
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 31
    Eureka:
    • Registration of Services: AP (a Client registers with the server instance and publishes its status
    every 30 seconds)
    • Lookup of Services: AP (a client receives the view of the one server it connects to)
    • „Self-Preservation“ if a network partition is suspected between Server/Server or Clients/Server:
    The server keeps the current status of all known services

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  32. Netflix Eureka
    Eureka – Pull and Cache instead of Query and Push (1/2)
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 32
    Etcd:
    • Service-Lookup with HTTP GET as synchronous call
    • Waiting for changes with HTTP GET blocking query („?wait=true&waitIndex=X“)
    Consul:
    • Service-Lookup with HTTP GET as synchronous call
    • Service-Lookup with HTTP GET as blocking query („?wait=Xs&index=Y“)

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  33. Netflix Eureka
    Eureka – Pull and Cache instead of Query and Push (1/2)
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 33
    Eureka:
    • Clients pull every 30 seconds the delta from the service registry of their server
    • Server pull every 30 seconds the delta from other servers
    • Service lookup is a client-local operation
    • A status change can take up to 2 minutes to be published to all participants
    (Lookup with HTTP GET as a synchronous call is available via API, but rarely used)

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  34. Getting Organized with Service Discovery for Microservices
    34
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016
    Everyday life in the cloud
    1
    etcd: Central Configuration Store
    2
    Consul: Service Discovery, Configuration and Monitoring
    3
    Eureka: Availability First!
    4
    Service Discovery Comparison
    5

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  35. Service Discovery Comparison
    Capability Matrix
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 35
    Etcd Consul Eureka
    Configurations Yes Yes No
    Service Discovery
    via REST-API
    Yes
    (via KV-Store)
    Yes Yes
    Write configuration files Yes
    (via confd)
    Yes
    (native and confd)
    No
    Dynamic DNS Yes
    (via SkyDNS)
    Yes
    (native)
    No
    Topology Support No Yes (Data center
    & WAN)
    Yes
    (Region & Zone)
    Access Controls SSL Client-Certificates Detailed (ACLs) Servlet-Security
    Health Checks for Services No Yes No
    Edge Service (Vulcan) (Fabio) (Zuul)
    GUI No Yes No

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  36. Service Discovery Comparison
    Who’s your favourite?
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 36
    Etcd – highly available Key-Value-Store
    • Part of CoreOS
    • Easy to use REST-API
    Consul – Services as „First Class Citizen“ in addition to Key-Value-Store
    • Active Monitoring of Services
    • Built in Security: Transport encryption und ACLs
    Eureka – Built for Amazon Cloud
    • Very good integration into the Amazon Infrastructure
    • Schedule-based replication of the complete service catalogue to the clients (Client Pull)
    • Availability first – Consistency second
    @ahus1de

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  37. Service Discovery Comparison
    Links
    © msg | Getting Organized with Service Discovery for Microservices | Alexander Schwartz | Continuous Lifecycle London 2016 | 4 May 2016 37
    HashiCorps Consul für Service Discovery,
    Monitoring und Konfigurationsmanagement
    http://heise.de/-3040847
    eBay Fabio:
    https://github.com/eBay/fabio
    Nomad:
    https://www.nomadproject.io/
    Saltstack and Consul Examples
    https://github.com/ahus1/saltconsul-examples
    @ahus1de
    CoreOS etcd: https://github.com/coreos/etcd
    Jurnous etcdj: https://github.com/jurmous/etcd4j
    Vulcan: http://www.vulcanproxy.com/
    SkyDNS: https://github.com/skynetservices/skydns
    Netflix Eureka: https://github.com/Netflix/eureka
    Apache Zookeeper: https://zookeeper.apache.org/
    Netflix exhibitor: https://github.com/Netflix/exhibitor
    HashiCorp Consul: http://consul.io/

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  38. .consulting .solutions .partnership
    Alexander Schwartz
    Principal IT Consultant
    +49 171 5625767
    [email protected]
    @ahus1de
    msg systems ag (Headquarters)
    Robert-Buerkle-Str. 1, 85737 Ismaning
    Germany
    www.msg-systems.com

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