open-vault/changelog/17678.txt at b74e4bc781e96beeb2c9cfacc1d57e5b6711caad - luxolus/open-vault - Stateless Git Forge

luxolus/open-vault

Christopher Swenson 19b3b8a7c6

Proposal: Remove debug symbols from build (#17678 )

By adding the link flags `-s -w` we can reduce the Vault binary size
from 204 MB to 167 MB (about 18% reduction in size).

This removes the DWARF section of the binary.

i.e., before:

```
$ objdump --section-headers vault-debug

vault-debug:	file format mach-o arm64

Sections:
Idx Name             Size     VMA              Type
  0 __text           03a00340 0000000100001000 TEXT
  1 __symbol_stub1   00000618 0000000103a01340 TEXT
  2 __rodata         00c18088 0000000103a01960 DATA
  3 __rodata         015aee18 000000010461c000 DATA
  4 __typelink       0004616c 0000000105bcae20 DATA
  5 __itablink       0000eb68 0000000105c10fa0 DATA
  6 __gosymtab       00000000 0000000105c1fb08 DATA
  7 __gopclntab      02a5b8e0 0000000105c1fb20 DATA
  8 __go_buildinfo   00008c10 000000010867c000 DATA
  9 __nl_symbol_ptr  00000410 0000000108684c10 DATA
 10 __noptrdata      000fed00 0000000108685020 DATA
 11 __data           0004e1f0 0000000108783d20 DATA
 12 __bss            00052520 00000001087d1f20 BSS
 13 __noptrbss       000151b0 0000000108824440 BSS
 14 __zdebug_abbrev  00000129 000000010883c000 DATA, DEBUG
 15 __zdebug_line    00651374 000000010883c129 DATA, DEBUG
 16 __zdebug_frame   001e1de9 0000000108e8d49d DATA, DEBUG
 17 __debug_gdb_scri 00000043 000000010906f286 DATA, DEBUG
 18 __zdebug_info    00de2c09 000000010906f2c9 DATA, DEBUG
 19 __zdebug_loc     00a619ea 0000000109e51ed2 DATA, DEBUG
 20 __zdebug_ranges  001e94a6 000000010a8b38bc DATA, DEBUG
```

And after:

```
$ objdump --section-headers vault-no-debug

vault-no-debug:	file format mach-o arm64

Sections:
Idx Name            Size     VMA              Type
  0 __text          03a00340 0000000100001000 TEXT
  1 __symbol_stub1  00000618 0000000103a01340 TEXT
  2 __rodata        00c18088 0000000103a01960 DATA
  3 __rodata        015aee18 000000010461c000 DATA
  4 __typelink      0004616c 0000000105bcae20 DATA
  5 __itablink      0000eb68 0000000105c10fa0 DATA
  6 __gosymtab      00000000 0000000105c1fb08 DATA
  7 __gopclntab     02a5b8e0 0000000105c1fb20 DATA
  8 __go_buildinfo  00008c20 000000010867c000 DATA
  9 __nl_symbol_ptr 00000410 0000000108684c20 DATA
 10 __noptrdata     000fed00 0000000108685040 DATA
 11 __data          0004e1f0 0000000108783d40 DATA
 12 __bss           00052520 00000001087d1f40 BSS
 13 __noptrbss      000151b0 0000000108824460 BSS
```

The only side effect I have been able to find is that it is no longer
possible to use [delve](https://github.com/go-delve/delve) to run the
Vault binary.

Note, however, that running delve and other debuggers requires access
to the full source code, which isn't provided for the Enterprise, HSM,
etc. binaries, so it isn't possible to debug those anyway outside of
people who have the full source.

* panic traces
* `vault debug`
* error messages
* Despite what the documentation says, these flags do *not* delete the
function symbol table (so it is not the same as having a `strip`ped
binary).

It contains mappings between the compiled binary and functions,
paramters, and variables in the source code.

Using `llvm-dwarfdump`, it looks like:

```
0x011a6d85:   DW_TAG_subprogram
                DW_AT_name	("github.com/hashicorp/vault/api.(*replicationStateStore).recordState")
                DW_AT_low_pc	(0x0000000000a99300)
                DW_AT_high_pc	(0x0000000000a99419)
                DW_AT_frame_base	(DW_OP_call_frame_cfa)
                DW_AT_decl_file	("/home/swenson/vault/api/client.go")
                DW_AT_external	(0x01)

0x011a6de1:     DW_TAG_formal_parameter
                  DW_AT_name	("w")
                  DW_AT_variable_parameter	(0x00)
                  DW_AT_decl_line	(1735)
                  DW_AT_type	(0x00000000001e834a "github.com/hashicorp/vault/api.replicationStateStore *")
                  DW_AT_location	(0x009e832a:
                     [0x0000000000a99300, 0x0000000000a9933a): DW_OP_reg0 RAX
                     [0x0000000000a9933a, 0x0000000000a99419): DW_OP_call_frame_cfa)

0x011a6def:     DW_TAG_formal_parameter
                  DW_AT_name	("resp")
                  DW_AT_variable_parameter	(0x00)
                  DW_AT_decl_line	(1735)
                  DW_AT_type	(0x00000000001e82a2 "github.com/hashicorp/vault/api.Response *")
                  DW_AT_location	(0x009e8370:
                     [0x0000000000a99300, 0x0000000000a9933a): DW_OP_reg3 RBX
                     [0x0000000000a9933a, 0x0000000000a99419): DW_OP_fbreg +8)

0x011a6e00:     DW_TAG_variable
                  DW_AT_name	("newState")
                  DW_AT_decl_line	(1738)
                  DW_AT_type	(0x0000000000119f32 "string")
                  DW_AT_location	(0x009e83b7:
                     [0x0000000000a99385, 0x0000000000a99385): DW_OP_reg0 RAX, DW_OP_piece 0x8, DW_OP_piece 0x8
                     [0x0000000000a99385, 0x0000000000a993a4): DW_OP_reg0 RAX, DW_OP_piece 0x8, DW_OP_reg3 RBX, DW_OP_piece 0x8
                     [0x0000000000a993a4, 0x0000000000a993a7): DW_OP_piece 0x8, DW_OP_reg3 RBX, DW_OP_piece 0x8)
```

This says that the particular binary section is the function
`github.com/hashicorp/vault/api.(*replicationStateStore).recordState`,
from the file `/home/swenson/vault/api/client.go`, containing
the `w` parameter on line 1735 mapped to certain registers and memory,
the `resp` paramter on line 1735 mapped to certain reigsters and memory,
and the `newState` variable on line 1738, mapped to certain registers,
and memory.

It's really only useful for a debugger.

Anyone running the code in a debugger will need full access the source
code anyway, so presumably they will be able to run `make dev` and build
the version with the DWARF sections intact, and then run their debugger.

2022-11-02 10:47:13 -07:00

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Raw Blame History

	```release-note:improvement
	`Reduced binary size`
	```