Allow for custom images

[nnovaeshc]

Describe Request:

I would like to have the option to configure this orb so it can use a custom image. Currently there’s an outage in docker registry and we don’t have an SLA with them but do have an SLA with AWS ECR service, so I’d rather use an image hosted there.

Examples:

Supporting Documentation Links:

[thedoc31]

I am seconding this, as our corporate policy requires we use an internal dockerhub mirror, and in addition to @nnovaeshc 's dockerhub outage, docker hub's rate limiting restrictions [1] can also cause a similar problem which will break the build.

Additionally, we need to have the option to authenticate to pull whatever image we set the orb to use, specifically for the case of an image hosted in a private docker registry.

[1]

Error response from daemon: toomanyrequests: You have reached your pull rate limit. You may increase the limit by authenticating and upgrading: https://www.docker.com/increase-rate-limit

[NicolasLemince]

I tried something: #108

[honstar]

This is exactly what I need as well 👍 The ability to specify a custom executor and hence pulling a docker image from a corporate mirror would avoid running into potential rate limiting, causing false positive build failures.