Symlinks not working when mounting HNS-enabled blob storage usind ADLS

[jlabhard-sg]

Which version of blobfuse was used?

2.1.1-preview.1

Which OS distribution and version are you using?

Ubuntu 22.04

If relevant, please share your mount command.

sudo blobfuse2 mount ${mount_dir} --config-file="/etc/blobfuse_${storage_container}_config.yml --use-adls=true"

Config:

allow-other: true

# Logger configuration
logging:
  type: base
  level: log_debug
  file-path: '/.blobfuse2.log'
  max-file-size-mb: 512
  file-count: 10
  track-time: true

# Pipeline configuration. Choose components to be engaged. The order below is the priority order that needs to be followed.
components:
  - libfuse
  - stream
  - attr_cache
  - azstorage

# Libfuse configuration
libfuse:
  default-permission: '0666'
  attribute-expiration-sec: 120
  entry-expiration-sec: 120
  negative-entry-expiration-sec: 240

# Streaming configuration
stream:
  # If block-size-mb, blocks-per-file or cache-size-mb are 0, the stream component will not cache blocks.
  block-size-mb: 8
  max-buffers: 3
  buffer-size-mb: 512

# Attribute cache related configuration
attr_cache:
  timeout-sec: 7200

# Azure storage configuration
azstorage:
# Required
  type: adls
  account-name: ${storage_account}
  container: ${storage_container}
  endpoint: https://${storage_account}.blob.core.windows.net/
  # Optional
  block-size-mb: 16
  max-concurrency: 32
  mode: spn
  tenantid: ${tenantid}
  clientid: ${clientid}
  clientsecret: ${clientsecret}

# Health Monitor configuration
health_monitor:
  output-path: /var/log/
  enable-monitoring: true
  stats-poll-interval-sec: 10
  process-monitor-interval-sec: 30
  # list of monitors to be disabled
  monitor-disable-list:
    - cpu_profiler
    - memory_profiler

What was the issue encountered?

The symlinks are not mounted. The name of the files appear but do no redirect to anything, readlink is empty, and cd returns Error: Not a directory.
Creating a symlink in the mounted directory after mounting also does not create a symlink, only a filename that appears when listing the directory.
Mounting the same storage using NFS instead of blobfuse does mount the symlinks.
Mounting another storage with HNS-disabled storage account using type: block does mount symlinks

Have you found a mitigation/solution?

Not using blobfuse.

Please share logs if available.

The mount is successful so there is no error log, but the symlinks don't work.

[vibhansa-msft]

Can you try out the same test case with file-cache instead of stream. Just want to pin point where the issue is.

[jlabhard-sg]

I tried using file-cache, but I have the same issue. With the following configuration:

# Logger configuration
logging:
  type: base
  level: log_debug
  file-path: '/.blobfuse2.log'
  max-file-size-mb: 512
  file-count: 10
  track-time: true

# Pipeline configuration. Choose components to be engaged. The order below is the priority order that needs to be followed.
components:
  - libfuse
  - file_cache
  - attr_cache
  - azstorage

libfuse:
  attribute-expiration-sec: 120
  entry-expiration-sec: 120
  negative-entry-expiration-sec: 240

file_cache:
  path: ${HOME}/tempcache
  timeout-sec: 120
  max-size-mb: 4096

# Attribute cache related configuration
attr_cache:
  timeout-sec: 7200

# Azure storage configuration
azstorage:
# Required
  type: adls
  account-name: ${storage_account}
  container: ${storage_container}
  endpoint: https://${storage_account}.blob.core.windows.net/
  # Optional
  block-size-mb: 16
  max-concurrency: 32
  mode: spn
  tenantid: ${tenantid}
  clientid: ${clientid}
  clientsecret: ${clientsecret}

# Health Monitor configuration
health_monitor:
  output-path: /var/log/
  enable-monitoring: true
  stats-poll-interval-sec: 10
  process-monitor-interval-sec: 30
  # list of monitors to be disabled
  monitor-disable-list:
    - cpu_profiler
    - memory_profiler

[vibhansa-msft]

How were these symlinks created on the container? If you have used blobfuse to create those you will see a meta property in the blobs that helps blobfuse to identify the file as a symlink. Can you share the listing output on shell for the similar files.

[souravgupta-msft]

@jlabhard-sg, we have fixed this bug in the PR #1283. It will be part of our next release.

To have symlink working in ADLS accounts, you can either,

• Set no-symlinks: false in the config file under attr_cache section.
• Or, pass the flag --no-symlinks=false in the mount command.

I also do want to point out that for ADLS accounts, if you're enabling symlink support, it can impact the directory list performance. By default, symlink is disabled for ADLS accounts.