Reorganize ExecutorTask to better distinguish between the task Spec and
the Status.
Split the task Spec in a sub part called ExecutorTaskSpecData that contains
tasks data that don't have to be saved in etcd because it contains data that can
be very big and can be generated starting from the run and the runconfig.
Currently, if no shell is defined in the task and in the step, the executor will
use an hardcoded default shell.
This will cause changed run behavior if we add an option to globally set the
agola default shell.
To avoid this set the task shell to the default shell inside the runconfig if
it's empty so future executions will always use this value.
Defining an option to override the user for a run step is too much fine grained
and, for consistency, will require to do the same also for the other steps
(clone, *workspace etc...).
Remove it since it's probably enough to define it at the task level.
On a git process error don't write the error message to the response body since
it'll break the git protocol and don't try to write the status header (since it's not
possible as it was automatically written by the go http server before writing
the body).
Currently we are using different `When` types for every service and convert
between them. This is a good approach if we want to keep isolated all the
services (like if we were using different repos for every service instead of the
current monorepo).
But currently, since When is identical between all the services, simplify this by
using a common When type.
Currently `advanceRunTasks` isn't deterministic and doesn't calculate the final
state in one call. So could happen that `getTasksToRun` will select a task to be
executed since its parent are finished (marked as skipped in advanceRunTasks)
but the task isn't marked to be skipped (because advanceRunTasks has calculated
this task before its parents).
Currently fix this doing the same task selection logic done in `advanceRunTasks`
and add a TODO to make `advanceRunTasks` be deterministic by processing tasks by
their level (from level 0).
In c1ff28ef9f we exported various types. Unfortunately the types used by cmd
variable create/update are the wrong types and marshalling fails. Fix it using
the right type. In future this internal types should be exported.
