Adding flyctl image show/update command

[davissp14]

Provides app image details:

$ flyctl image show --app <app-name>

Image details
  Registry   = registry.fly.io
  Repository = spring-star-1995
  Tag        = deployment-1631759185
  Version    = N/A
  Digest     = sha256:fb465a3f01184606d11bbee3376b1d0de48fc890408ea9119b477c9d7f5fa221

If version tracking is enabled ( currently only available for PG ), we will see version information and will also be notified when a new image version has become available.

$ flyctl image show --app <app-name>
Update available flyio/postgres:13 v0.0.0 -> flyio/postgres:13.4 v0.0.4
Run `fly image update` to migrate to the latest image version.

Image details
  Registry   = registry-1.docker.io
  Repository = flyio/postgres
  Tag        = 13
  Version    = v0.0.0
  Digest     = sha256:fb465a3f01184606d11bbee3376b1d0de48fc890408ea9119b477c9d7f5fa221

Latest image details
  Registry   = registry-1.docker.io
  Repository = flyio/postgres
  Tag        = 13.4
  Version    = v0.0.4
  Digest     = sha256:d90b1a8456d2c587ef04905269f39b89ffe3c20400095b0098757b26ad676aa5

Running flyctl image update --<app-name> will ask you to confirm the migration path. If accepted, it will issue a new deploy targeting the newest image version.

**Note: **

$ flyctl image update --app <app-name>
? Update `<app-name>` from flyio/postgres:13 v0.0.0 to flyio/postgres:13.4 v0.0.4? Yes
Release v60 created

You can detach the terminal anytime without stopping the update
Monitoring Deployment

8 desired, 8 placed, 8 healthy, 0 unhealthy [health checks: 24 total, 24 passing]
--> v60 deployed successfully

[jsierles]

Nice! How about some upgrade instructions? And perhaps a note about downtime or lack thereof? Is there a plan for something like fly postgres upgrade?

[davissp14]

@jsierles

Nice! How about some upgrade instructions? And perhaps a note about downtime or lack thereof? Is there a plan for something like fly postgres upgrade?

Yep! I'm going to be wiring up the upgrade logic this morning. I keep going back and forth on whether to add fly image upgrade or fly postgres upgrade or both. Have any opinions?

[michaeldwan]

@davissp14 if it's only for postgres right now you can nest it under postgres and not waste time making it generic until we need it for another db.

[davissp14]

@michaeldwan It's roughly the same amount of work either way. Either we run with flyctl postgres update, or flyctl image update and noop if image version tracking isn't enabled.

[michaeldwan]

Not sure this comment was before or after talking about it in slack 😄 shipit

[jsierles]

Is this PR ready? Would like to cut a release today :)

[davissp14]

@jsierles I'm hoping to wrap it up today, but I'll keep you posted as I have a few other things on my plate.

[kernel-io]

how would this function if you have forked the postgres-ha script (to add postgis for instance)?

[davissp14]

The update feature is currently only available to apps running our official postgres-ha image. In your case, it would just noop.