# Building Singularity containers on Transit :::danger **Disclaimer:** The purpose of the `transit` server is to transfer files to/from the `wharf` area in your sensiteve project. This tutorial is not an official documentation and does not give a guarantee that it will work for any case. If you experience problems following this material - please apply for small project on Rackham and use Rackham for this purpose. ::: :::warning Keep in mind that your $HOME folder is a read-only snapshot of your Rackham $HOME folder and has limit of 2.9GB write overlayer. ``` df -h | grep $USER overlay 2.9G 4.0K 1.3G 1% /gorilla/home/XXXXX ``` ::: 1. Login to `transit.uppmax.uu.se` Documentation: - https://uppmax.github.io/UPPMAX-documentation/cluster_guides/transfer_bianca/#transit-server 2. Mount the `wharf` of your project. ```bash user@transit:~$ mount_wharf sens2023531 Mounting wharf (accessible for you only) to /home/<user>/sens2023531 <user>-sens2023531@bianca-sftp.uppmax.uu.se's password: ``` 3. Navigate to your `wharf` folder ```bash cd sens2023531 ``` 4. Disable Singularity cache ```bash export APPTAINER_DISABLE_CACHE=true export APPTAINER_TMPDIR=/dev/shm/$USER mkdir -p $APPTAINER_TMPDIR unset ${!NXF_*} ``` *Note:* Alternatively, redirect the `APPTAINER_TMPDIR` to your `wharf` folder to allow for larger container builds. This approach will be **much slower**, though. 5. Build/pull your container as usual. ## Contacts: - [Pavlin Mitev](https://katalog.uu.se/profile/?id=N3-1425) - [UPPMAX](https://www.uu.se/en/centre/uppmax) - [AE@UPPMAX - related documentation](/8sqXISVRRquPDSw9o1DizQ)