cf CLI for real: push, bind and logs, the three you use every day

The cf CLI is the command-line interface that manages applications and services in Cloud Foundry. It has a huge catalog of commands, but let’s be honest: 90% of your daily work is three verbs. Deploy, bind a service and look at the logs when something breaks. The rest you look up when you need it.

The anatomy of a cf command

Every cf command follows the same structure: the tool, the command, the arguments and the options. A mental model before the practice:

• cf: invokes the tool.
• command: the main action (push, bind-service, logs).
• arguments: required values, such as the app name.
• command options: dash-prefixed modifiers, like -f to force or -t for target.

flowchart LR
  L["cf login / target"] --> P["cf push: deploy"]
  P --> BS["cf bind-service: bind"]
  BS --> RS["cf restage: apply the binding"]
  RS --> LG["cf logs: observe"]

push: upload the application

cf push uploads and starts an application. You can pass parameters inline or, better, in a manifest.yml:

# deploy reading the directory's manifest
cf push

# or explicit: name, memory and buildpack
cf push my-app -m 256M -b nodejs_buildpack

# check the state of what's deployed
cf apps

bind: connect services

An app with no data is useless. bind-service connects a service instance (HANA, XSUAA) to the application, injecting its credentials. The binding does not take effect until the app is re-prepared:

# create the service instance
cf create-service hana hdi-shared my-hdi

# bind the instance to the app
cf bind-service my-app my-hdi

# apply the binding: the app restarts with the new credentials
cf restage my-app

# list the space's services
cf services

The restage is the step everyone forgets on day one. You bind, nothing happens, and you lose half an hour before realizing the binding materializes when the app is re-prepared.

logs: see what’s really happening

When the app won’t start or returns a 503, the logs are the only source of truth:

# tail the logs live
cf logs my-app

# recent dump without staying attached to the stream
cf logs my-app --recent

The operator who doesn’t read logs guesses. The one who guesses deploys three times what a single line of cf logs --recent would have solved.

Next post: what’s inside VCAP_SERVICES and why credentials should never live in your code.