Treat your CLI like an API

Applying the developer-friendly attributes of APIs to your command line interfaces will increase adoption of your software, make it easier to update over time, and build trust in your business.

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1. Rob Szumski @robszumski | Head of Design Treat your CLI like an API
2. Smart Datacenter Powered by containers
3. Automatic Updates
4. Treat your CLI like an API CLI API =
5. Why do I care about CLIs? ?
6. Critical Path
7. UX = Adoption = Revenue Embedded in a dev workflow But, devs need to trust it first
8. Versioning Plan for greater scope Backwards compatibility Deprecation/feature removal Great APIs...
9. Design your CLI like an API CLI API =
10. Design your CLI like an API CLI API =
11. Design your CLI like an API CLI API =
12. Design your CLI like an API CLI API = UI
13. First, a history lesson
14. Do one thing & do it well UNIX PHILOSOPHY
15. Users expect full solutions, which increases CLI scope
16. Remote services have unique data models
17. Developers expect many features with knobs to tweak
18. “Cloud native”
19. “Cloud native” Dynamic Large scope Remote services Integrated Security Release Cycles Configuration
20. Easy to configure Well-named commands Useful release notes Out-of-box experience
21. Versioning/backwards compatibility Always scriptable Easy to upgrade Document the upgrade Building trust
22. Living in the Critical Path LESSONS FROM
23. Automatic Updates apt/yum npm pypi docker curl | sh Package Managers
24. Choose smart, secure defaults FLAGS
25. $ mysql $ mysql --host=localhost --port=3306
26. $ rkt run ubuntu $ rkt run \ --insecure-options=none \ --trust-keys-from-https=false \ ubuntu
27. Think about forward compatibility at the beginning FLAGS
28. $ rkt run --insecure-skip-verify \ ubuntu $ rkt run --insecure-options=image \ ubuntu $ rkt run \ --insecure-options=image,http,pubkey \ ubuntu
29. Scripting against a CLI should always be possible This is a hidden API contract CLI/API CONTRACT
30. $ kubectl get pods NAME READY STATUS RESTARTS AGE etcd-torus 1/1 Running 0 1d installer-prototype-sksfg 1/1 Running 0 13d nginx-router-lhdy6 1/1 Running 0 13d sidenav-prototype-gffv1 1/1 Running 0 6d tectonic-console-sd0rr 1/1 Running 0 13d torus-5mo0j 1/1 Running 0 1d torus-n4sji 1/1 Running 0 1d torus-p8c4z 1/1 Running 0 1d $ kubectl get pods | grep nginx | tr -s ' ' | cut -d ' ' -f 1 nginx-router-lhdy6
31. Provide flags for users Env vars for scripts CLI/API CONTRACT
32. $ etcd \ --listen-peer-urls http://10.0.1.10:2380 \ --listen-client-urls http://127.0.0.1:2379 $ ETCD_LISTEN_PEER_URLS=http://10.0.1.10:2380 \ ETCD_LISTEN_CLIENT_URLS=http://127.0.0.1:2379 \ etcd
33. 12:21:47 Starting etcd2... 12:21:47 recognized and used environment variable ETCD_ADVERTISE_CLIENT_URLS=http://10.0.0.50: 2379 12:21:47 recognized and used environment variable ETCD_DATA_DIR=/var/lib/etcd2 12:21:47 recognized and used environment variable ETCD_ELECTION_TIMEOUT=1200 12:21:47 recognized and used environment variable ETCD_INITIAL_ADVERTISE_PEER_URLS=http://10. 0.0.50:2380 12:21:47 recognized and used environment variable ETCD_INITIAL_CLUSTER=controller=http://10. 0.0.50:2380 12:21:47 recognized and used environment variable ETCD_LISTEN_CLIENT_URLS=http://0.0.0.0:2379 12:21:47 recognized and used environment variable ETCD_LISTEN_PEER_URLS=http://0.0.0.0:2380 12:21:47 unrecognized environment variable ETCD_NAEM=controller 12:21:47 etcd Version: 2.3.2 12:21:47 Git SHA: ce63f10 12:21:47 Go Version: go1.5.4 12:21:47 Go OS/Arch: linux/amd64 12:21:47 setting maximum number of CPUs to 1, total number of available CPUs is 1 12:21:47 the server is already initialized as member before, starting as etcd member... 12:21:47 listening for peers on http://0.0.0.0:2380 12:21:47 listening for client requests on http://0.0.0.0:2379 12:21:48 recovered store from snapshot at index 8240824
34. 12:21:47 Starting etcd2... 12:21:47 recognized and used environment variable ETCD_ADVERTISE_CLIENT_URLS=http://10.0.0.50: 2379 12:21:47 recognized and used environment variable ETCD_DATA_DIR=/var/lib/etcd2 12:21:47 recognized and used environment variable ETCD_ELECTION_TIMEOUT=1200 12:21:47 recognized and used environment variable ETCD_INITIAL_ADVERTISE_PEER_URLS=http://10. 0.0.50:2380 12:21:47 recognized and used environment variable ETCD_INITIAL_CLUSTER=controller=http://10. 0.0.50:2380 12:21:47 recognized and used environment variable ETCD_LISTEN_CLIENT_URLS=http://0.0.0.0:2379 12:21:47 recognized and used environment variable ETCD_LISTEN_PEER_URLS=http://0.0.0.0:2380 12:21:47 unrecognized environment variable ETCD_NAEM=controller 12:21:47 etcd Version: 2.3.2 12:21:47 Git SHA: ce63f10 12:21:47 Go Version: go1.5.4 12:21:47 Go OS/Arch: linux/amd64 12:21:47 setting maximum number of CPUs to 1, total number of available CPUs is 1 12:21:47 the server is already initialized as member before, starting as etcd member... 12:21:47 listening for peers on http://0.0.0.0:2380 12:21:47 listening for client requests on http://0.0.0.0:2379 12:21:48 recovered store from snapshot at index 8240824
35. Return info required for the next step CLI/API CONTRACT
36. $ kubectl create -f nginx.yaml Created pod nginx-router-lhdy6 $ docker run -d ubuntu a736b91c5bd9627671d4fe952103b1422cc123ce40ded73703184577730fce10 $ etcdctl member add infra3 http://10.0.1.13:2380 added member 9bf1b35fc7761a23 to cluster ETCD_NAME="infra3" ETCD_INITIAL_CLUSTER="infra0=http://10.0.1.10:2380,infra1=http: //10.0.1.11:2380,infra2=http://10.0.1.12:2380,infra3=http://10. 0.1.13:2380" ETCD_INITIAL_CLUSTER_STATE=existing
37. Balance scope with discoverability INFORMATION ARCHITECTURE
38. $ preso add-slide --title="New Slide" $ preso slide add --title="New Slide"
39. $ preso -h Usage: preso [flags] preso [command] Available Commands: add-slide apply-template delete-slide make-template present
40. $ preso -h Usage: preso [flags] preso [command] [subcommand] Available Commands: slide present template Use "preso [command] --help" for info about a command.
41. $ preso add-slide $ preso slide add
42. Build Trust
43. > Open-source CLIs
44. Design your CLI like an API CLI API =
45. Design your CLI like an API CLI API =
46. CoreOS is hiring! Rob Szumski Head of Design @robszumski