document versioning

docs/VERSIONING.md

@@ -0,0 +1,47 @@
+# Summary
+
+
+```
+                       ┌──────────────────────────┐
+                 ┌─────┤ diracx/base:YYYY.MM.DD.P ├─────┐
+                 │     └──────────────────────────┘     │
+                 │                                      │
+┌────────────────▼──────────────────┐  ┌────────────────▼───────────────┐
+│ diracx/services-base:YYYY.MM.DD.P │  │ diracx/tasks-base:YYYY.MM.DD.P │
+└────────────────┬──────────────────┘  └────────────────┬───────────────┘
+                 │                                      │
+     ┌───────────▼────────────┐              ┌──────────▼──────────┐
+     │ diracx/services:v0.X.Y │              │ diracx/tasks:v0.X.Y │
+     └────────────────────────┘              └─────────────────────┘
+
+```
+
+
+# Dependencies
+
+
+duplication between setup.cfg and environment.yaml
+
+diracx/base: Dockerfile with environment.yml (basically python version)
+diracx/services-base: diracx/base Image + Dockerfile + environment.yml (fastapi +
+whatever service needs)
+diracx/services image: diracx/service-base + Dockerfile + pip install --no-dependencies diracx-service
+diracx/tasks-base image: diracx/base Image + Dockerfile + environment.yml (gfal2 + htcondor + whatever tasks needs)
+diracx/tasks image: diracx/tasks-base + Dockerfile + pip install --no-dependencies diracx-tasks
+
+
+
+# Image versioning
+
+diracx/base, diracx/service-base and diracx/tasks-base are versionned by date and regenerated every Monday. The ``latest`` tag moves along.
+
+A DiracX release results in the creation of new DiracXService and diracx/tasks images, base on  **specific** diracx/base tags (not ``latest``), which is the latest at this point in time
+
+This way, we are sure that whatever run in production is stable.
+
+As for the DiracX tests, they can start from the ``latest`` base images, and do `pip install` with allowed dependencies
+
+
+# DiracX versioning
+
+It is too early to decide on a proper long term scheme, but for the forseable future (DIRAC is around), we will have v0.<major>.<minor>.