fix: use the non-root atlantis user instead of root (cherry-pick #3886)

[jamengual]

what

• Make standard use of the atlantis user and not root.
• Removed gosu, as we're using the atlantis user anyways
• Set DOCKER_CONTENT_TRUST=1 anywhere we build

why

• gosu has various security issues reported (see reported issues)
• it's not a good practice to use the root user by default

tests

references

• Original PR fix: use the non-root atlantis user instead of root #3886
• Closes Run docker container as atlantis instead of root #3777
• Partially fixes Fix dockle container security issues #3789

[fzipi]

Probably we don't need this now?

atlantis/Dockerfile

Line 56 in fefedad

libcap2 \

and

atlantis/Dockerfile

Line 167 in fefedad

libcap~=2.69 \

[jamengual]

Probably we don't need this now?

atlantis/Dockerfile

Line 56 in fefedad

libcap2 \

and

atlantis/Dockerfile

Line 167 in fefedad

libcap~=2.69 \

I do not recall why this was added, why do you think is not needed?

[fzipi]

Probably we don't need this now?

atlantis/Dockerfile

Line 56 in fefedad

libcap2 \

and

atlantis/Dockerfile

Line 167 in fefedad

libcap~=2.69 \

I do not recall why this was added, why do you think is not needed?

This is just to have the setcap binary, which we are removing...

[GenPage]

This is a cherry-picked PR, the original is already merged. Please open a new PR to remove libcap

Probably we don't need this now?

atlantis/Dockerfile

Line 56 in fefedad

libcap2 \

and

atlantis/Dockerfile

Line 167 in fefedad

libcap~=2.69 \

I do not recall why this was added, why do you think is not needed?

This is just to have the setcap binary, which we are removing...