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Environment variables

s1bursts reads credentials and SNAP settings from environment variables. Set them in your shell, or keep them in a .env file:

.env
CDSE_USERNAME=your-account-name
CDSE_PASSWORD=your-password
SNAP_MAX_RAM_GB=16

s1bursts does not read .env by itself. Run your script with uv run --env-file .env script.py, or call dotenv.load_dotenv() from python-dotenv at its start.

Warning

Keep .env out of version control, since it holds your password.

CDSE credentials

Downloads need a CDSE account, but searching needs none. The S3 keys are optional and enable a second download route, which takes over when CDSE’s burst service fails:

Variable Purpose
CDSE_USERNAME, CDSE_PASSWORD CDSE account, used by the burst service
CDSE_S3_ACCESS_KEY_ID, CDSE_S3_SECRET_ACCESS_KEY CDSE S3 keys, from the S3 key manager
CDSE_S3_PROFILE Instead of the two keys: a profile in ~/.aws/credentials that holds them

SNAP

SNAP needs plenty of memory. SNAP_MAX_RAM_GB is the total budget shared by all parallel SNAP processes. s1bursts reserves 3 GB of it for overhead and splits the rest between the processes, so the default of 8 GB gives one process 5 GB. That is enough for backscatter and coherence. Raise the budget when you run several processes in parallel:

Variable Purpose Default
SNAP_BIN The SNAP installation’s bin directory gpt on PATH
SNAP_MAX_WORKERS SNAP processes run in parallel 1
SNAP_MAX_RAM_GB Memory budget across those processes, in GB 8
SNAP_THREADS_PER_JOB Threads per SNAP process CPU count divided by workers
SNAP_CACHE_RATIO Share of each process’s memory used as tile cache 0.7
SNAP_TIMEOUT Seconds one SNAP process may run before it is stopped and its burst recorded as failed, or none for no limit 3600
SNAP_AUXDATA_PATH Cache for orbit files and DEM tiles ~/.snap/auxdata
SNAP_DEM_CACHE Cache for prepared external DEMs ~/.s1bursts/dem

SNAPConfig sets the same values in code and takes precedence over the environment. See Processing with SNAP.

Temporary files

SNAP writes large uncompressed files while it works, in the folder that TMPDIR names. Point TMPDIR at a local disk with several GB free, since on many systems the default /tmp is held in memory.